A Word of Caution for Users of Supplemental Melatonin

A new study is suggesting a link between long-term melatonin use and an increased risk of heart failure, but experts say there's no need for alarm—at least not yet. Researchers reviewed health records from more than 130,000 adults with chronic insomnia, finding that those who took prescribed melatonin for a year or more were twice as likely to develop heart failure, more than three times as likely to be hospitalized for heart failure, and nearly two times as likely to die from any cause compared to nonusers over five years, per NBC News. However, sleep specialists and cardiologists caution that the study, set to be presented at an American Heart Association conference, is observational and not yet peer-reviewed.

Critics point out several limitations, including the possibility that some "nonusers" may have taken over-the-counter melatonin, which could skew the results. Experts also emphasize that the study only shows an association, not causation. Others point out that poor sleep is associated with higher heart rates and blood pressure, and more cardiovascular events. Still, the findings "warrant attention, especially given the widespread perception of melatonin as a benign, 'natural' sleep aid," a rep for the American Academy of Sleep Medicine tells the Washington Post. Melatonin is a hormone produced by the brain to signal sleep, but many doctors remain unconvinced of the long-term effectiveness or safety of melatonin supplements, especially for chronic insomnia.

While some research has suggested possible heart benefits for melatonin, those studies tend to be small or short-term. The new research did not account for dosage or whether melatonin actually improved sleep in the patients studied. Experts say further study into long-term melatonin use is needed. For now, most specialists recommend using melatonin only in low doses and for short periods, such as to address jet lag or shift work, per the Post. Cognitive behavioral therapy remains the preferred treatment for chronic insomnia. Experts advise that people, especially those with heart issues, consult with their doctors before making any changes.